Area protection in the vicinity of automated manufacturing machines or in the vicinity of potentially hazardous processes is becoming increasingly important. Area protection is designed to prevent personnel, or even other automated equipment, from intentionally or accidentally entering a work area while a robot or other machine is performing its automatic function. Depending on the machine being enclosed, it may also be important for the area protection to provide a physical barrier between the machine and the surrounding area, as may be the case where an automatic welder is enclosed, and flying sparks and debris need to be contained. Area protection may also provide a barrier to radiation, or heat, or noise generated by the enclosed equipment. At the same time, it is desirable for any area protection system to allow unfettered access to the machine at appropriate time: between cycles, for replenishment of raw materials or work pieces, etc. Of course, area protection may also be used to enclose non-automated processes, such as manual welding stations and the like.
A variety of area protection systems have been used in the past. So-called light curtains comprise an array of photo-sensitive detectors surrounding a doorway or opening adjacent the automated machine. If the detectors sense the presence of an object (personnel or equipment) in the doorway, operation of the machine may be halted. While this may prevent accidental contact with the operating machine, light curtains do not provide a physical barrier against entry, nor do they offer a physical barrier to debris, sparks, radiation, etc. that may emanate from the enclosed equipment. Pressure-sensitive mats disposed on the floor adjacent a door or other opening near an automated machine serve the same purpose, but are similarly limited. Mechanical gates or barriers are also used. However, these tend to be slow-moving and may prevent visual access to the equipment being enclosed, as well as being relatively expensive. Movable, or portable barriers or screens may also be used, but these must be manually moved whenever access to the enclosed machine or work area is desired.